There is known a game device for displaying an image representing a scene obtained by viewing a virtual three-dimensional space in which a character object from a given viewpoint. For example, there is known a game device which realizes a soccer game by displaying an image of a scene obtained by viewing a virtual three-dimensional space in which a character object representing a soccer player is placed from a given viewpoint.
In such a game device, in order to change the posture and the facial expression of the character object, a plurality of skeleton parts are set for the character object. The skeleton comprises a joint which corresponds to a joint portion and a bone which connects between joints. To each joint and bone, at least some of vertices of polygons forming the character object are correlated. When the states (position and rotational angle) of the joint and the bone change, the positions of the vertices correlated to the joint and the bone change based on the changes of the states of the joint and the bone. That is, the posture and the facial expression of the character object change.
FIG. 10 shows an example of a head portion 46a of a character object 46. FIGS. 11 and 12 show example states of an eye 50 of the character object 46. FIG. 11 shows a state where the eye 50 of the character object 46 is completely opened and FIG. 12 shows a state where the eye 50 of the character object 46 is completely closed. Reference numeral 52 represents an upper eyelid of the eye 50 of the character object 46, and reference numeral 56 represents a lower eyelid of the eye 50 of the character object 46. In addition, reference numeral 54 represents a representative vertex among the vertices of the upper eyelid 52, and reference numeral 58 represents a representative vertex among the vertices of the lower eyelid 56.
FIG. 13 shows an example of a skeleton which is set for the character object 46 comprising a plurality of polygons. FIG. 13 shows a joint 60 for controlling opening and closing of the eye 50 of the character object 46. In the character object 46, for example, a joint, a bone, or the like for controlling opening and closing of the mouth of the character object 46 are also set, but these are not shown in FIG. 13.
To the joint 60, for example, vertices (representative vertex 54 or the like) of the upper eyelid 52 of the character object 46 are correlated. The positions of the vertices of the upper eyelid 52 change according to the state (rotational angle) of the joint 60. In other words, the vertices of the upper eyelid 52 move according to the joint 60. FIG. 14 is a diagram for explaining a relationship between the upper eyelid 52 of the character object 46 and the joint 60. In the state where the eye 50 of the character object 46 is completely opened (refer to FIG. 11), if the joint 60 rotates with the X axis as a rotational axis, in an A direction (refer to FIG. 13), by a predetermined angle θc (for example, 30°), the upper eyelid 52 of the character object 46 moves to the lower eyelid 56. For example, the representative vertex 54 (predetermined vertex) of the upper eyelid 52 moves from a base position (first position) to a position (second position) of the representative vertex 58 of the lower eyelid 56. Thus, a state where the eye 50 of the character object 46 is completely closed is realized (refer to FIG. 12). On the other hand, in the state where the eye 50 of the character object 46 is completely closed (refer to FIG. 12), if the joint 60 rotates with the X axis as the rotational axis, in a direction opposite to the A direction (refer to FIG. 13), and by a predetermined angle θc (for example, 30°), the upper eyelid 52 of the character object 46 returns to the base position. In other words, the state returns to a state where the eye 50 of the character object 46 is completely open (refer to FIG. 11).
In the above-described game device, the joint and the bone are controlled by motion data. The motion data is data defining changes of states of the joint and bone in a case where the posture and facial expression of the character object 46 are changed. For example, the motion data during closing of the eye 50 of the character object 46 is data defining a change of the rotational angle of the joint 60 for every predetermined period (for example, every 1/60th of a second). The motion data is, for example, the data indicating that the joint 60 is gradually rotated with the X axis as the rotational axis, in the A direction, until the rotational angle of the joint 60 reaches a predetermined angle θc (for example, 30°). With the joint 60 rotating according to the motion data, the scene of the character object 46 closing the eye 50 is shown on the game screen.
In addition, the game device as described above may sometimes have a character transformation function, that is, a function to allow a player to change a model shape of the character object 46. For example, in some cases, the player can change the size (narrowness) of the eye 50 of the character object 46.
[Patent Document] JP 2007-082677 A